Apparatus for drying culture media and analogous materials



Dec; 27, 1955 H. L. SMITH, JR

APPARATUS FOR DRYING CULTURE MEDIA AND ANALOGOUS MATERIALS Filed May 1, 1953 United States Patent APPARATUS FOR DRYING CULTURE MEDIA AND ANALOGOUS MATERIALS Horace Smith, Jr., Richmond, Va.

Application May 1, 1953, Serial No. 352,531

7 Claims. (Cl. 159-42) This invention relates to the drying of culture media, pharmaceutical materials, heat-sensitive food products, and other similar semi-liquid substances, and has for its principal object the provision of an improved apparatus for effecting continuous dehydration of such materials in a more facile and efficient manner than has been heretofore proposed.

Essentially, this is accomplished by subjecting a thin stratum or film of the material adherent to one face of an endless traveling metallic belt to the action of radiant heat directed toward both faces of such belt, with means being provided whereby the quantity of heat reaching each face of the belt, and preferably different portions of each such face, may be easily, quickly and efficiently varied at will as conditions may require. The belt and other elements appurtenant thereto preferably are enclosed in a housing from which the air is evacuated, and which is provided with means whereby the dried product may be removed as desired without loss of vacuum. The water vapors resulting from the drying may be removed from the enclosure by any of several conventional methods, e. g., by the employment of steam jets; through absorption by a dried dessicant such as silica gel; by collection on refrigerated surfaces upon which they will freeze; or by condensation by sprays of refrigerated lithium chloride or other low vapor pressure condensing liquid.

The essential elements of a typical example of the present apparatus are illustrated in the accompanying drawing forming a part of this specification, in which the figure is a longitudinal vertical sectional view, partly in elevation and to some extent diagrammatic.

Referring to said drawing in greater detail, a thin end less stainless-steel or similar metal belt 10 is trained about a pair of spaced rotatably mounted pulleys 11 and 12, the former of which maybe driven in the direction indicated by the arrow by any appropriate source of power (not shown), and the latter of which is provided with a peripheral compartment 13 through which cold water or other cooling medium may be circulated by means of the hollow shaft 14 and the induction and eduction pipes 15 and 16, whereby the temperature of. the dried product may be suitably reduced prior to discharge from the drier. A receptacle 17 is disposed below the starting end of the lower run of the belt 10 adjacent the pulley 12, to which receptacle the culture medium or other substance to be dried is supplied through a pipe 19. A roll 20 rotatably mounted in said receptacle dips into the medium 18 and its peripheral face engages the under surface of the belt 10 whereby it may transfer a thin layer or film of the medium to such surface. A presser roll 21 is provided above the belt to insure continuous contact of the belt with the transfer roll 20, as will be readily understood from the drawing.

A chambered radiating element 22 is mounted in spaced parallel relation to each face of each run of the belt 10, such elements being of a width to span the belt transversely and of a length to extend throughout a major portion of the distance between the pulleys 11 and 12. A

heating medium such as steam, or preferably a heat transfer liquid of the chlorinated bi-phenyl type, is enculated through the chambers 23 of said elements by means of suitable supply pipes 24 and 25 and return pipes 26 and 27.

interposed between each radiator element 22 and that face of the belt adjacent thereto is a series of adjustable heat-reflecting members 30, each of which comprises a transversely extending metal slat carried by an oscillatably mounted rod or shaft 31. These members are volitionally adjustable between the vertical position in which some of them are shown and the inclined positions in which others are illustrated, and in the former position they interpose substantially no interference to the flow of heat from their associated radiating element 22 to the adjacent belt face, while in the latter position they intercept and reflect such heat away from such face to a degree dependent upon their inclination from the vertical. These reflectors thus provide a simple and effective means for controlling the heat being received by each face of the belt from the several radiator elements, and of quickly varying the amount of such heat as conditions may require.

The reflecting members 30 may be individually adjust-.

able if desired but preferably they are interconnected in sets of two or more for unitary adjustment. That surface of each member which faces toward its associated radiating element 22 when the member is inclined, preferably is highly polished whereby to have a maximum reflecting power. The parts thus far described are enclosed in a housing 35 from which the air may be evacuated through a pipe 36 connected to any suitable vacuum pump. A hopper 37 is provided within said housing beneath the cooling pulley 12 for receiving the dried material, which is scraped from the belt 10 as it passes about such pulley by a doctor blade 38. The hopper communicates with a pair of discharge passages 39 in the bottom wall of the housing 35, and is provided with a swingable vane 40, shifting of which causes the material to be directed to one passage or theother as desired. Each passage 39 is controlled by a valve 41, normally closed to preserve the vacuum within the housing, and below each valve there is a fitting 42 to which may be attached a bottle or other receptacle 43 for receiving the product. Piping 44, controlled by valves 45, is adapted to supply nitrogen or similar inert gas to the fittings 42 whereby to break the vacuum below the valves 41 after a container 43 has been filled and th I valve therefor closed. 3

What is claimed is:

1. Apparatus for drying culture media and analogous,

semi-liquid materials, comprising an endless metal belt traversably mounted upon a pair of spaced pulleys;

means for continuously applying a film of the material.

to be dried to the outward face of said belt; a chambered radiating element mounted in spaced parallel relation to each face of the belt intermediate said pulleys; means for circulating a heating fluid through the chambers of said elements, whereby they may emit radiant heat toward each of said belt faces; a plurality of adjustably mounted heat-reflecting members disposed between each of said radiating elements and the adjacent face of the belt, said members being severally adjustable to control the heat reaching various areas of the belt from said radiating elements; and means for removing the dried material from the belt.

2. Apparatus for drying culture media and analogous heated lluid through the chambers of said elements, whereby they may emit radiant heat toward each of said belt faces; a series of oscillatably mounted parallel metallic slats extending transversely 'of the belt intermediate each of said radiating elementsand the belt face adjacent thereto, said slats having heat-reflectingsurfaces and being arranged in sets each of which is volitionally adjustable whereby to vary the amount of heat reaching various longitudinal areas of the belt from said elements; and means for removing the dried material from the belt.

3. Apparatus for drying culture media and analogous semi-liquid materials, comprising an endless metallic belt; a pair of spaced-pulleys about which the belt is trained, one of said pulleys having a peripheral compartment;

means for circulating a cooling fluid through said pulley compartment; means for driving, one of said pulleys; means adjacent said compartmented pulley for depositing a film of the material vto be dried upon the outward face of. said belt; chambered heat radiating elements disposed in spaced parallel relation to each, face of the belt inter mediate said pulleys; means for circulating a heating medium throughthe chambers of said radiating elements; means disposed between the radiating elements .and the belt for controlling at will the amount of heat received by various longitudinally adjacent areas of the belt and the material thereon from such'elements; and .means adjacent said chambered pulley for removing the dried material from the belt.

4. Apparatus for drying culture media and analogous semi-liquid materials, comprising a housing providing a closed chamber; means for evacuating the air from said chamber; an endless metallic belt mounted upon a pair of spaced pulleys within the chamber to provide spaced upper and lower belt runs, one of said pulleys having a peripheral compartment; means for circulating a cooling fluid through said pulley compartment; means for driving said pulleys and belt; means adjacent the starting end of said lower belt run for continuously depositing afilm of the material to be dried upon the outward face'of said belt; heat radiating means extending in spaced parallel relation to each face of each run of the belt between the pulleys; means disposed between the belt and each of said radiating means for volitionally varying the amount of heat reaching various longitudinal areas of the belt and material thereon from such radiating means; means for removing the dried material from the belt; a hopper within said chamber for receiving the material from said removing means, said hopper communicating with discharge passages in a wall of the chamber; and valve means controlling'said passages.

5. Apparatus for drying culture media and analogous semi-liquid materials, comprising an endless metallic belt trained about a pair of spaced pulleys toprovide elongated spaced upper and lower belt runs; means for -driv-- ing one of said pulleys to continuously traverse said beltruns between'them; means adjacent the beginning of said-lower belt run for continuously applying a thin coatingof the material to be dried to the under surface of suchrun; a chambered radiating element fixedly mounted in spaced relation to each face of each of said belt runs and extending parallel thereto throughout substantially the length of such runs; means for circulating a heating fluid through the chambers of said elements whereby the elements may emit radiant heat toward each of 'said'belt' faces; a series of adjustably mounted heatrefie'ctingmembers disposed between each of said radiating elements and the face of the belt run adjacent there to, the various members of each such series being volitionally adjustable to intercept or pass heat from said elements to selected longitudinal areas of their associated belt runs whereby to control the drying of the material; and means adjacent the final end of the upper belt run for removing the dried material from the belt.

6. Apparatus for drying culture media and analogous semi-liquid materials, comprising a pair of spaced pulleys having an imperforate endless metal belt trained about and extending between them in elongated substantially paralllel upper and lower runs; means for driving one of said pulleys to continuously move said belt about them; means adjacent the point of departure of the lower run of the belt from one of the pulleys for continuously applying a thin layer of the material to be dried to the under surface of said lower belt run; a chambered radiating element fixedly mounted adjacent each face of each of said belt runs and extending in spaced parallel relation to the respective faces throughout a major portion of the length thereof; means for circulating a heating fluid through the chambers of said elements whereby they may emit radiant heat toward each of said belt faces; means for volitionally varying the heat reaching longitudinally contiguous areas of the respective belt runs whereby to control the drying of the material, such means comprising a series, of adjacent adjustably mounted heat-reflecting members disposed between each of said radiating elements and the face of the belt adjacent thereto, which members are adjustable to intercept or pass heat from the radiating elements to said belt faces, and the members of each series being arranged in independently adjustable longitudinally adjacent sets, each of which comprises a plurality of the members interconnected for simultaneous adjustment; and means adjacent the last mentioned pulley for removing the dried material from the belt.

7. In apparatus for the vacuum drying of heat-sensitive, biologically-active substances (and analogous liquid and semi-liquid substances) of the type including a vacuum chamber, ,a continuously movable endless belt for carrying the substance to be dried during the drying operation, means for heating the substance on said belt, means for applying the undried substance to said belt while maintaining said belt in motion and holding a vacuum in said chamber, and means for removing the dried substance from said belt while maintaining said belt in motion and holding a vacuum in said chamber, the improvement including, in combination, at least two means for supporting said belt during motion thereof spaced apart and providing a run for said belt between them, at least one hollow radiator means disposed to radiateheat onto said run, means for circulating afluid.

heat transfer medium through said radiator, and variable radiation interceptor means disposed between said run and said radiator.

References Citedjn the tile of thispatent UNITED STATESPATENTS 784,854 Grace Mar. 14, 1905 1,696,613 Shroyer Dec. 25, 1928 2,131,666 McDougall Sept. 27, 1938 2,188,401 Crowley Jan. 30, 1940 2,349,300 Olsen May 23, 1944 2,620,573 McMahon Dec.'9, 1952 2,666,994 Dungler Ian; 26, 1954 FOREIGN PATENTS 99,815 Switzerland June 16, 1923 338,286 Great Britain Nov.- 20-, 1930 

